code: def flat_node_and_edge(nodes):
      """flat_node_and_edge"""
      nodes = list(set(traverse(nodes)))
      return nodes
  
imports: import os
  import tqdm
  import yaml
  import pgl
  import time
  import copy
  import numpy
  import os.path
  from pgl.utils.logger import log
  from pgl.graph import Graph
  from pgl import graph_kernel
  from pgl.sampling.custom import subgraph
  from ogb.lsc import MAG240MDataset, MAG240MEvaluator
  from dataset.base_dataset import BaseDataGenerator
  import time
label_desc: Use image node_id 3 for calling a global function with example usage: flat_node_and_edge(nodes) and returns: nodes